Packaging for fingerprint sensors and methods of manufacture

ABSTRACT

A fingerprint sensor package, including a sensing side for sensing fingerprint information and a separate connection side for electrically connecting the fingerprint sensor package to a host device, is disclosed. The fingerprint sensor package can also include a sensor integrated circuit facing the sensing side and substantially surrounded by a fill material. The fill material includes vias at peripheral locations around the sensor integrated circuit. The fingerprint sensor package can further include a redistribution layer on the sensing side which redistributes connections of the sensor integrated circuit to the vias. The connections can further be directed through the vias to a ball grid array on the connection side. Some aspects also include electrostatic discharge traces positioned at least partially around a perimeter of the connection side. Methods of manufacturing are also disclosed.

RELATED CASES

This Application claims priority to U.S. Provisional Application61/453,460, entitled PACKAGING FOR FINGERPRINT SENSORS AND METHODS OFMANUFACTURE, filed on Mar. 16, 2011, the disclosure of which is herebyincorporated by reference in its entirety for all purposes, as if theentire disclosure, specification and drawings, were completelyreproduced in this application.

BACKGROUND OF THE DISCLOSED SUBJECT MATTER

Conventional fingerprint sensors include an integrated circuit, such asa silicon die, with an exposed top surface portion for receiving humantouch. Due to the exposed top surface, packaging of the integratedcircuit can be difficult. For example, conventional packages encapsulatethe integrated circuit while exposing a portion of the top surface, butmust provide room for wire connections from the top surface toperipheral connection points on a substrate below the integratedcircuit. The substrate is provided with additional connection points inorder to allow connection of the fingerprint sensor package to a hostdevice. See, U.S. Pat. No. 7,251,351 issued Jul. 31, 2007, to Mathiassenet al. for Sensor Unit, Especially for Fingerprint Sensors; U.S. Pat.No. 6,710,41 issued Mar. 23, 2004, to Chou et al. for Wafer LevelPacking of Micro Electromechanical Device.

Some fingerprint sensors provide the silicon die attached to anunderside of a flexible substrate, where human touch over the top of theflexible substrate can be sensed indirectly by the silicon die, asdiscussed in U.S. Pat. No. 7,099,496, issued to Benkley, on Aug. 29,2006, entitled SWIPED APERTURE CAPACITIVE FINGERPRINT SENSING SYSTEMSAND METHODS, and U.S. Pat. No. 7,751,601, issued on Jul. 6, 2010, toBenkley, entitled FINGER SENSING ASSEMBLIES AND METHODS OF MAKING, bothof which are assigned to the assignee of the present application andincorporated by reference. In such fingerprint sensors, the silicon dieis either attached directly under the surface to be touched for sensingthrough the flexible substrate, or attached remote from the surface tobe touched and a separate array of metal traces in communication withthe silicone die is located directly under the surface to be touched forsensing through the flexible substrate. Rigid substrates or rigid basesmust be coupled to the flexible substrate or positioned under theflexible substrate to provide support for the flexible substrate and/orthe silicon die when connected to a host device.

Kim et al., “Application of Through Mold Via (TMV) as PoP Base Package,”2008 Electronic Components and Technology Conference, IEEE (2008)discusses the application of through mold vias (“TMV”) in a “fan-out”wafer level packaging (“WLFO package”) arrangement for a package onpackage (“PoP”) device. The disclosure of Kim et al. is incorporated byreference.

SUMMARY

An aspect of the disclosed subject matter provides a fingerprint sensorpackage including a sensing side for sensing fingerprint information anda separate connection side for electrically connecting the fingerprintsensor package to a host device. The fingerprint sensor package can alsobe adapted and configured to include a sensor integrated circuit facingthe sensing side and substantially surrounded by a fill material.Additionally, the fill material can include vias at peripheral locationsaround the sensor integrated circuit. The fingerprint sensor package canfurther be adapted and configured to include a redistribution layer onthe sensing side which redistributes connections of the sensorintegrated circuit to the vias. The connections can further be directedthrough the vias to a ball grid array on a connection side. Some aspectsalso include electrostatic discharge traces positioned at leastpartially around a perimeter of the connection side.

Another aspect of the disclosure provides for the fabrication of thesensors.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference,for all possible purposes and to the same extent as if the disclosure ofwhich was reproduced in the present application in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the disclosed subject matter are set forth withparticularity in the appended claims. A better understanding of thefeatures and advantages of the present disclosed subject matter will beobtained by reference to the following detailed description that setsforth illustrative embodiments, in which the principles of the disclosedsubject matter are utilized, and the accompanying drawings of which:

FIG. 1 is a perspective view of a fingerprint sensor packageincorporated into a host device with a flush configuration;

FIG. 2 is another perspective view of a fingerprint sensor packageincorporated into a host device with a beveled configuration;

FIG. 3 is a top perspective view of a connection side of the fingerprintsensor package of FIG. 1;

FIG. 4 is a cross-sectional view of the fingerprint sensor package ofFIG. 1;

FIG. 5 is a flow chart of a process for fabricating fingerprint sensorpackages;

FIG. 6 is a top view of a silicon wafer according to one step of theprocess of FIG. 5;

FIG. 7 is a top view of redistributed silicon die according to anotherstep of the process of FIG. 5;

FIG. 8 is a top view of the redistributed silicon die according toanother step of the process of FIG. 5;

FIG. 9 is a top view of the redistributed silicon die according toanother step of the process of FIG. 5;

FIG. 10 is a bottom view of the redistributed silicon die according toanother step of the process of FIG. 5;

FIG. 11 is a partly enlarged bottom view of the redistributed silicondie according to another step of the process of FIG. 5;

FIG. 12 is a top view of a plurality of separated fingerprint sensorpackages according to another step of the process of FIG. 5;

FIG. 13 is a cross-sectional view of another embodiment of a fingerprintsensor package;

FIG. 14 is a bottom view of a connection side of an isolated fingerprintsensor package of FIGS. 11-13;

FIG. 15 is a cross-sectional view of a plurality of fingerprint sensorpackages of FIG. 13 prior to separation;

FIG. 16 is an exploded view of redistributed silicon die and interposerboards prior to separation during fabrication of the fingerprint sensorpackages of FIGS. 13-15;

FIG. 17A is a top view of a sensing side of an interposer board of thefingerprint sensor package of FIGS. 13-15;

FIG. 17B is a bottom view of a connection side of the interposer boardof the fingerprint sensor package of FIGS. 13-15;

FIG. 18 is a cross-sectional view of an additional possible embodimentof the disclosed subject matter;

FIG. 19 is a cross-sectional view of an additional possible embodimentof the disclosed subject matter;

FIG. 20 is a cross-sectional view of an additional possible embodimentof the disclosed subject matter;

FIG. 21 shows a wafer populated with a plurality of die forming aplurality of main fingerprint imaging sensor circuitry integratedcircuits;

FIG. 22 shows a secondary IC, such as containing micro-metalizationsforming, e.g., biometric object sensing elements like capacitive coupleddrivers and pick-ups or electronic circuits, such as like light emittingdiodes (“LEDS”) according to aspects of the disclosed subject matter;

FIG. 23 shows an example of redistribution of the fingerprint sensorinto a co-molded wafer (“CMW”) according to aspects of embodiments ofthe disclosed subject matter.

FIG. 24 illustrates redistribution of fingerprint sensor ICs andsecondary ICs into a co-molded wafer (“CMW”) according to aspects ofembodiments of the disclosed subject matter;

FIG. 25 illustrates the placement of a mold ring around the CMWaccording to aspects of embodiments of the disclosed subject matter;

FIG. 26 shows an example of the injection of fill material to furtherform the CMW according to aspects of embodiments of the disclosedsubject matter;

FIG. 27 illustrates a top view of the CMW prior to the applicationelectrical redistribution layers according to aspects of embodiments ofthe disclosed subject matter;

FIG. 28 also illustrates a top view of CMW prior to RDL layers beingapplied, according to aspects of embodiments of the disclosed subjectmatter;

FIG. 29 illustrates the placement of solder balls on the CMW accordingto aspects of embodiments of the disclosed subject matter;

FIG. 30 illustrates a top view of the sawing apart of CMWs intoindividual WLFO packaged devices.

FIG. 31 illustrates a bottom view of the sawing of the CMW intoindividual WLFO packaged devices.

DETAILED DESCRIPTION

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the disclosed subject matter. Variousmodifications to the illustrated embodiments will be readily apparent tothose skilled in the art, and the generic principles herein can beapplied to other embodiments and applications without departing fromembodiments of the disclosed subject matter. Thus, embodiments of thedisclosed subject matter are not intended to be limited to embodimentsshown, but are to be accorded the widest scope consistent with theprinciples and features disclosed herein. The following detaileddescription is to be read with reference to the figures, in which likeelements in different figures have like reference numerals. The figures,which are not necessarily to scale, depict selected embodiments and arenot intended to limit the scope of embodiments of the disclosed subjectmatter. Skilled artisans will recognize the examples provided hereinhave many useful alternatives which fall within the scope of embodimentsof the disclosed subject matter and/or the appended claims.

FIGS. 1 and 2 illustrate a package 10 for a biometric object sensor,e.g., a fingerprint sensor package 10, according to aspects of thedisclosed subject matter. The fingerprint sensor package 10 can includea sensing side 12, a connection side 14, and a mold filler material 16between the sensing side 12 and the connection side 14. As shown inFIGS. 1 and 2, the fingerprint sensor package 10 can be incorporatedinto a separate product or device 18 (e.g., a host device). For example,the connection side 14 can be electrically coupled to a substrate 20 ofthe device 18 and the sensing side 12 can be exposed through a cutout 22in a device housing 24 of the device 18. In one aspect, the sensing side12 can be flush with an outer surface 23 of the device housing 24, asshown in FIG. 1. In another aspect, the device housing 24 can bebeveled, i.e., formed with bevels 27 around the cutout 22 so that thesensing side 12 can be substantially below the outer surface 23, asshown in FIG. 2.

As shown in FIGS. 1-3, the connection side 14 can include a ball gridarray (“BGA”) 25, comprising a plurality of solder balls 26 toelectrically couple the connection side 14 to the device substrate 20.In addition, as shown in FIG. 4, the fingerprint sensor package 10 caninclude a sensor integrated circuit 28, a sensing side redistributionlayer 30, a sensing side coating or ink layer 32, and a connection sideredistribution layer 34.

In at least some aspects, the sensing side redistribution layer 30 caninclude a metal layer 36 with metal redistribution traces 36′, a metalsensor array (not shown), and, optionally, additional metal traces (notshown). The metal layer 36 can be positioned between a first passivationlayer 38 and a second passivation layer 40, as shown in FIG. 4. Thesensor array (not shown) can include a plurality of conductive traces(not shown), such as copper traces, for providing image sensing todetect the ridges and valleys of a fingerprint as a finger moves acrossthe sensing side 12 and/or velocity sensing to detect the speed of afinger moving across the sensing side 12, as is shown by way of examplein the Benkley references cited above.

Fingerprint information sensed by the sensor array (not shown) can betransmitted to the sensor integrated circuit 28 via wireless or wiredcommunication technologies. For example, in one aspect, a circuit side42 of the sensor integrated circuit 28 (e.g., the side facing thesensing side 12) can include a radio frequency receiver (not shown) andeach trace of the sensor array (not shown) can include a radio frequencytransmitter (not shown) for transmitting the sensed fingerprintinformation to the radio frequency receiver (not shown). In otheraspects, the sensor integrated circuit 28 can include a plurality ofradiofrequency receivers (not shown), e.g., formed on the sensor side 42of the integrated circuit 28, for receiving information transmitted fromone or more of the radio frequency transmitter traces (not shown) of thesensor array (not shown), e.g., also formed on the sensor side 42 of theintegrated circuit 28. The sensor integrated circuit 28 can also includedrive and sense electronics for interpreting the fingerprint informationreceived. In addition, the sensing side coating layer 32 can providesubstantial protection against mechanical abrasion and/or mechanicalwear of the sensor integrated circuit 28 and the sensing sideredistribution layer 30, while such traces as may be formed on thesensor side 42 of the integrated circuit 28 can be similarly protectedby layers 30 and 32.

In other aspects, the circuitry on the sensor side 42 of the sensorintegrated circuit 28 can include an embedded pixel array (not shown)for directly sensing fingerprint information. In one example, theembedded pixel array (not shown) can sense fingerprint informationthrough the sensing side redistribution layer 30 and/or the sensing sidecoating layer 32. In another example, the embedded pixel array (notshown) can be substantially exposed on the sensing side 12 so that thefinger directly touches the sensor integrated circuit 28 for sensing,e.g., through an opening formed in the layers 30 and 32. The sensorintegrated circuit 28 can also include the drive and sense electronicsfor interpreting the fingerprint information sensed by the pixel array(not shown).

The mold filler 16 can provide the fingerprint sensor package 10 withsubstantial strength and durability, and can substantially protect thesensor integrated circuit 28 from physical damage. As shown in FIG. 4,the mold filler 16 can include through-mold vias (“TMVs”) 44 whichextend through the mold filler 16. The TMV vias 44 can allow connectionbetween the sensing side redistribution layer 30 and the connection sideredistribution layer 34. More specifically, the sensing sideredistribution layer 30 can have redistribution connections 46 from thesensor/circuit side 42 of the sensor integrated circuit 28, such as bondpad connections 46′, also shown in an embodiment of FIG. 18, toperipheral connection locations 48 at the vias 44. The connection sideredistribution layer 34 can redistribute from the connection locations48, through the TMV vias 44, to BGA 25 individual solder balls 26, e.g.,attached at connection points 50. As a result, the connections 46 fromthe sensor integrated circuit 28 can be electrically routed to the BOA25 solder ball connectors 26 on the connection side 14 by theredistribution layers 30, 34. Fingerprint information received andinterpreted by the sensor integrated circuit 28 can then be communicatedto the device 18 through the BGA 25 to the device substrate 20 (shown inFIG. 1 by way of example). In conventional fingerprint sensor packages,encapsulated wire bonds (not shown) can be routed from a sensing side 12around the sensor integrated circuit 28 to a connection side 14. In someaspects, the TMV vias 44 replace encapsulated wire bond connections (notshown), which can substantially decrease the thickness and/or area ofthe fingerprint sensor package 10 compared to conventional fingerprintsensor packages. Also, as shown in FIG. 4, the TMV vias 44 can be filledwith a filler material 52, for example, to add further structuralstrength and rigidity to the package 10.

Conventional electronic components, such as integrated circuits 28 infingerprint sensor packages 10, can be exposed to electrostaticdischarge (ESD) from various different sources, such as the human body(e.g., during a finger swipe). Contact between the sources and agrounded integrated circuit can generate large enough currents throughthe integrated circuit to cause significant damage. As shown in FIG. 3,the fingerprint sensor package 10 can include ESD discharge traces 54etched or otherwise formed, as described below, at least partiallyaround a perimeter of the connection side 14. The ESD discharge traces54 can be connected to a known potential, such as ground. For example,as shown in FIG. 3, the ESD discharge traces 54 can be connected torespective solder balls 26′ in the BGA 25 for connection to a knownpotential through the substrate 20 of the host product or device 18.

ESD can build up on the sensing side 12 as a user swipes his or herfinger. This charge can continue to increase in potential until the pathof least resistance is found and the charge is dissipated. The ESDdischarge traces 54 can create the shortest discharge path for ESD, thuspreventing ESD from discharging to the sensor integrated circuit 28 orany other components of the fingerprint sensing package 10 andpotentially damaging them. In some aspects, the ESD discharge traces 54can completely surround the outside perimeter of the connection side 14.In other aspects, the ESD discharge traces 54 can partially surround theoutside perimeter of the connection side 14. Also, in some aspects, theESD discharge traces 54 can be positioned on the sensing side 12 tocompletely or at least partially surround the sensor array (not shown).

FIGS. 5-12 illustrate a wafer-level fan out (“WLFO”) process forfabricating the fingerprint sensor package 10 according to an aspect ofthe disclosed subject matter. First, as shown in FIG. 6, at step 56, asilicon wafer 58 containing a plurality of die 60 (i.e., formingelectronic circuitry such as the sensor integrated circuits 28 of FIGS.1, 2 and 4) can be probed to test the functionality of each die 60. Atstep 62, the silicon wafer 58 can be mounted onto a film 64, whichprovides support during sawing of the die 60. At step 66, the die 60 canbe sawed apart and cleaned and, at step 68, each die 60 can be marked(e.g., with a bar code label, not shown) for identification purposes. Atstep 70, an adhesive can be applied to a sticky tape 72 or similarproduct for receiving the separated die 60. At step 74, separate die 60can be redistributed onto the sticky tape 72 with sufficient spacing 76between each die 60, as shown in FIG. 7. At step 78, a mold ring 80 canbe placed around the sticky tape 72, as shown in FIG. 8, and the moldfiller 16 can be filled around and over the redistributed die 60 tocreate a new wafer 82 of partially-constructed packages, as shown inFIG. 9. The mold filler 16 can be added at a height or thickness tocompletely cover the die 60, i.e., rendering them not visible from theside of the molded wafer 82 shown in FIG. 9. For example, in one aspect,the mold filler 16 can have a height or thickness of between about 700micrometers and about 800 micrometers. At step 84, the new wafer 82 canbe demounted from the sticky tape 72, i.e., exposing the die 60 on theopposite side from that shown in FIG. 9.

At steps 86 and 88, the new wafer 82 can be turned over for processingof layers on the sensing side 12, as shown in FIG. 10. Morespecifically, at step 86, the sensing side redistribution layer 30, asdescribed above, can be applied to the sensing side 12. The sensing sideredistribution layer 30 can include a metal layer 36 positioned betweena first passivation layer 38 and a second passivation layer 40, asdescribed above. The metal layer 36 can provide for electricalconnections 46 on each die 60, such as bond pads, to connectionlocations 48 beside, or around, each die 60 (e.g., within the spacing 76in the mold filler 16 between the die 60). The metal layer 36 can alsoprovide the sensor array (not shown) for providing the image sensordrive and pick-up connections and/or the velocity sensor drive andpick-up connections, as appropriate. In some aspects, the sensing sideredistribution layer 30 can substantially cover the entire circuit side42 of the sensor integrated circuit 28. In other aspects, the sensingside redistribution layer 30 can provide an opening to expose theembedded pixel array on the sensor integrated circuit 28. At step 88,the entire sensing surface 12 of the new wafer 82, including the sensingside redistribution layer 30, can be coated with the sensing sidecoating layer 32, which can be ink or another suitable hard coatingmaterial. In some aspects, the embedded pixel array (not shown) can alsobe coated by the sensing side coating layer 32. In other aspects, theembedded pixel array (not shown) can remain exposed.

In some aspects, the sensing side redistribution layer 30 can have athickness between about 22.5 micrometers and about 31 micrometers. Forexample, the first passivation layer 38, e.g., formed of a dielectric,such as, amorphous silicon dioxide (“SiO₂”), can have a thickness ofabout 11 micrometers, the metal layer 36 can have a thickness of about 9micrometers, and the second passivation layer 40, e.g., also of SiO₂ canhave a thickness of about 11 micrometers. In addition, in some aspects,the sensing side coating layer 32 can have a thickness of between about15 micrometers and 25 micrometers. In some aspects, the thickness of thesecond passivation layer 40 and the sensing side coating layer 32 may bethin enough to allow sufficient sensing of fingerprint information bythe sensor array (not shown), which may be formed, e.g., in the metallayer 36 or on the sensor side 42 of the integrated circuit 28.

Following processing of the sensing side 12, the new wafer 82 can beturned over for processing of the connection side 14. At step 90, themold filler 16 can be laser ablated from the connection side 14 tocreate vias 44 in line with the electrical redistribution connectionlocations 48 on the sensing side 12. At step 92, the connection sideredistribution layer 34 can be applied to the connection side 14including, at step 94, applying a copper layer 34 to the connection side14 and, at step 96, etching the copper to provide routing connections,e.g., from the vias 44 to BGA 25 connection points 50. Also, at step 96,etching of the copper can provide electrostatic discharge traces 54, asdescribed above, between the die 60. At step 98, the vias 44 can befilled with a filler material 52 and at step 100, the BGA 25 solderballs 26 can be attached at the BGA 25 connection points 50, as shown,e.g., in FIGS. 4 and 11.

Following attachment of the BOA 25 solder balls 26, the packages can belaser marked (e.g., on the connection side 14) at step 102 withadditional identification information. At step 104, final testing can beperformed on the packages. At step 106, individual fingerprint sensorpackages 10 can be separated, as shown in FIG. 12, followed by a finalvisual inspection at step 108 and packing for shipment at step 110.

In some aspects, the fingerprint sensor package 10, as shown in FIGS.1-4, can have a length of about 11 millimeters and a width of about 2.5millimeters. The area of the sensor array on the sensing side 12 can beabout 20 micrometers by about 100 micrometers, or less, in some aspects.The length and the width of the fingerprint sensor package 10 can besubstantially smaller than conventional fingerprint sensor packages,which can permit a smaller opening 22 within the housing 24 of the hostdevice 18 for the fingerprint sensor package 10. In addition, theconnection side 14 of the fingerprint sensor package 10 can be surfacemounted to the substrate 20 of the device 18 directly below the opening22. As a result, the fingerprint sensor package 10 can take up lessspace compared to conventional fingerprint sensor packages which mayrequire additional space on the underside of the housing 24 forconnection to the device substrate 20.

FIGS. 13-17B illustrate the fingerprint sensor package 10 according toanother embodiment of the disclosed subject matter. As shown in FIG. 13,the fingerprint sensor package 10 can include a sensor integratedcircuit 28, mold filler material 16, a sensing side electricalredistribution layer 30, a sensing side coating layer 32, and a BGA 25,with solder balls 26. The fingerprint sensor package 10 can also includeinterposer boards 112 on either side of the sensor integrated circuit28. The interposer boards 112 can include plated and/or metal-filledvias 114. On the sensing side 12, the sensing side redistribution layer30 can electrically connect the connections 46 of the sensor integratedcircuit 28 with connections 48 for the vias 114. In one embodiment, onthe connection side 14, the BGA 25 solder balls 26 can be attacheddirectly to connection points 50 on each of the vias 114, as shown inFIGS. 13 and 14. In another embodiment, the BGA 25 solder balls 26 canbe connected to the vias 114 through a connection side redistributionlayer (not shown).

As shown in FIG. 13, the fingerprint sensor package 10 can also includeESD discharge castellations 116 (e.g., partial vias). The ESD dischargecastellations 116 can at least partially surround the outer edges of thefingerprint sensor package 10 and can be electrically connected to aknown potential, such as ground, in order to provide a dissipationpathway for ESD and to protect the sensor integrated circuit 28. In someaspects, the ESD discharge castellations 116 can be formed from the vias114 on the interposer boards 112 which are substantially split in half,as described below.

As shown in FIG. 15, multiple fingerprint sensor packages 10 can befabricated in wafer form and then sawed apart (e.g., along saw lines117). For example, in one embodiment, the fingerprint sensor packages 10can be fabricated according to the following method.

A silicon wafer including a plurality of die 60 (i.e., sensor integratedcircuits 28) can be sawed apart and the die 60 can be distributed on asticky tape or similar material so that the circuit side 42 of the die60 are attached to the sticky tape. Also, a panel of interposer boards112 can be split apart and the individual interposer boards 112 can bedistributed onto the sticky tape in between the die, for example in theorientation shown in FIG. 16. FIG. 17A illustrates an example sensingside 118 of the interposer boards 112 which can be applied to the stickytape, and later electrically connected to the die 60, as describedbelow. FIG. 17B illustrates an example connection side 120 of theinterposer boards 112, which can later be connected to BGA 25 solderballs 26, as described below.

After the die 60 and the interposer boards 112 are distributed onto thesticky tape, the mold filler 16 can be applied to substantially coverand fill between the die 60 and the interposer boards 112, substantiallyfixing the die 60 and the interposer boards 112 in place in relation toone another and creating a new wafer. The sticky tape can be removed anda sensing side redistribution layer 30 can be applied to the sensingside 12 of the new wafer. The sensing side redistribution layer 30 canelectrically connect the die 60 and the interposer boards 112, asdescribed above. The sensing side redistribution layer 30 can alsoinclude the metal sensor array (not shown) including the image sensordrivers and pick-ups (not shown) and/or the velocity sensor drivers andpick-ups (not shown). The sensing side redistribution layer 30 can becoated, for example with a sensing side coating layer 32. The connectionside 14 of the new wafer can be laser ablated to expose BGA 25 solderball 26 connection points 50 on the interposer boards 112 and the BGA 25solder balls 26 can then be applied to the BGA 25 solder ball 26connection points 50. The new wafer can then be sawed apart at the sawlines 117, as shown in FIGS. 15 and 16, substantially splitting each ofthe interposer boards 112 to separate individual fingerprint sensorpackages 10 and to expose the ESD discharge castellations 116 along atleast some of the outer side walls of each of fingerprint sensorpackages 10. Metal layers can also be added on the other side walls.

In one embodiment, the fingerprint sensor package 10, as shown in FIGS.13-17B, can have a thickness of about 1.1 millimeters. For example, thesensing side coating layer 32 can be about 25 micrometers thick, thesensing side redistribution layer 30 can be about 22.5 micrometersthick, the mold filler 16 can be about 800 micrometers thick (e.g., tosubstantially cover the sensor integrated circuit 28, which can be about620 micrometers in thickness), and the BGA 25 solder balls 26 height canbe about 250 micrometers. In addition, in some aspects, the fingerprintsensor package 10, as shown in FIGS. 13-17B, can have a length less thanabout 12 millimeters and a width less than about 3 millimeters. The areaof the sensor array (not shown) on the sensing side 12 can be about 20micrometers by about 5 micrometers, or less in some aspects.

Turning now to FIGS. 18-20 there are shown cross sectional views ofother possible embodiments of the disclosed subject matter. Anotherembodiment of the sensor package 10, as illustrated by way of example inFIG. 18 can have the connection side 14 including a multilayer printedcircuit board (“MLPCB”) 150. The MLPCB 150 may have mounted on it solderballs 26 forming the ball grid array 25, mounted on solder ballconnection pads 50. The solder ball connection pads 50 can be connectedelectrically to the metal layers in the sensing side 14 of thefingerprint sensor WLFO package through TMV vias 44 formed in the fillmaterial 16, and internal vias in the PCB 150 (not shown). The TMV vias44 may be connected to electrical connectors 50 on the PCB 150 throughsolder 152 and the PCB 150 may be connected to the WLFO package througha layer of adhesive 154. FIGS. 18-20 also illustrate metal pad 46′connecting the vias 46 to the silicon of the IC device 42. FIGS. 18-20also illustrate a SiPO dielectric layer 164. The WLFO package of FIG. 19has the fill material 16 in an opening in a PCB layer 150, such that thefill material 16 surrounds and encapsulates the IC die 42. Also throughvias 170 in the PCB layer material, filled with conducting material canprovide electrical connection between the solder ball mounting plates 50and the metal layers on the sensing side 12 of the package 10. FIG. 19also illustrates an example of sensor traces 146 connected to metal pads146,′ e.g., forming the drive plates and pick-up plates of the sensordevices. The WLFO package of FIG. 20 illustrates the fill layer 16extending all the way to the outer surface of the connection side,except for ball metal traces 50 and vias 44 and an ECD ring 160′.

If a package constructed using a supporting filler, such as a waferlevel fan out (“WLFO”) construction technique, and uses through is madewith through-mold vias (“TMVs”) formed through the molded fillermaterial, the package can be made much thinner. It is, also, much easierto do the TMV, if the WLFO is connected to a multilayer printed circuitboard “PCB”. Multilayer PCBs are relatively cheap, and can also be usedto adjust the height of the package very easily. A connection to acommon reference voltage, e.g., a grounded connection “EGND” 160 couldbe placed around the edge of the PCB 150, as seen, e.g., in FIG. 18 or160′ around the bottom lip, as seen, e.g., in FIG. 20, for ESDprotection. The WLFO with TMV can be connected to the PCB 150 portion ofthe package 10 with solder 152 and adhesive 154 (e.g., seen in FIG. 18).Cost could be reduced from a thicker WLFO plus TMV package, e.g. as seenin FIGS. 19 and 20, because the thickness of the WLFO with TMV can thenbe greatly reduced. This can also reduce the amount of time required forthe TMV laser ablation formation process.

FIG. 21 shows a wafer 58 populated with a plurality of die 60 forming aplurality of main fingerprint imaging sensor circuitry integratedcircuits. FIG. 22 shows a wafer of secondary ICs 61, such as, containingelectronic circuits, such as light emitting diodes (“LEDS”) 130, orother items utilized with or ancillary to or complimentary of the actualbiometric object sensor controller IC 42, and to be contained in thesame package, e.g., formed within the molded filler material 16 alongwith the IC 42, according to aspects of the disclosed subject matter.FIG. 23 shows an example of redistribution of the finger print sensorinto a co-molded wafer (“CMW”) 72 according to aspects of embodiments ofthe disclosed subject matter. FIG. 24 illustrates redistribution offingerprint sensor ICs and secondary ICs into a co-molded wafer (“CMW”)72 according to aspects of embodiments of the disclosed subject matter.FIG. 25 illustrates the placement of a mold ring 80 around the CMW 72according to aspects of embodiments of the disclosed subject matter.FIG. 26 shows an example of the injection of fill material 16 to furtherform the CMW 72 according to aspects of embodiments of the disclosedsubject matter. FIG. 27 illustrates a top view of the CMW 72 prior tothe application electrical redistribution layers. FIG. 28 alsoillustrates a top view of CMW prior to RDL layers being applied,according to aspects of embodiments of the disclosed subject matter.FIG. 29 illustrates the placement of solder balls 26 on the CMW 72 toform ball grid arrays 25, according to aspects of embodiments of thedisclosed subject matter. FIG. 30 illustrates the sawing apart of CMWs72 into individual WLFO packaged devices 10. FIG. 31 also illustratesthe sawing of the CMW into individual WLFO packaged devices.

While preferred embodiments of the present disclosed subject matter havebeen shown and described herein, it will be obvious to those skilled inthe art that such embodiments are provided by way of example only.Numerous variations, changes, and substitutions will now occur to thoseskilled in the art without departing from the disclosed subject matter.It should be understood that various alternatives to the embodiments ofthe disclosed subject matter described herein may be employed inpracticing the disclosed subject matter. It is intended that thefollowing claims define the scope of the disclosed subject matter andthat methods and structures within the scope of these claims and theirequivalents be covered thereby.

What is claimed is:
 1. A biometric object sensor wafer level fan outpackage, comprising: a sensor control integrated circuit; a molded fillmaterial formed to at least partially encapsulate the sensor controlintegrated circuit; a sensing side redistribution layer disposed on asensing side of the package, wherein the sensing side redistributionlayer comprises at least one passivation layer and a metal layer,wherein the metal layer of the sensing side redistribution layer furthercomprises metal redistribution traces and a metal sensor array in thesensing side redistribution layer, the metal sensor array furtherincluding a plurality of capacitively coupled drivers and pick-upsconfigured to detect ridges and valleys of a fingerprint; a connectionside redistribution layer disposed on a connection side of the package,wherein the connection side of the package is on an opposite side of thepackage relative to the sensing side; at least one ball grid arrayelectrical connector mounted on the connection side redistributionlayer; and a protective coating on the sensing side of the packagedisposed on the sensing side redistribution layer, wherein the moldedfill material completely encapsulates the sensor control integratedcircuit.
 2. The package of claim 1, wherein the molded fill materialcompletely encapsulates the sensor control integrated circuit.
 3. Thepackage of claim 1, wherein the at least one ball grid array electricalconnector is connected to the sensing side of the package through athrough mold via.
 4. The package of claim 1, further comprising: aprinted circuit board disposed on the connection side of the packagebetween the at least one ball grid array electrical connector and thesensor control integrated circuit.
 5. The package of claim 1, whereinthe molded fill material is formed in an opening of a printed circuitboard containing the sensor control integrated circuit.
 6. The packageof claim 1, wherein the package is a fingerprint sensor package.
 7. Thepackage of claim 1, further comprising: an interposer board disposedbetween the sensing side redistribution layer and the connection sideredistribution layer.
 8. The package of claim 1, wherein the connectionside redistribution layer comprises a multilayer printed circuit board.9. The package of claim 1 A biometric object sensor wafer level fan outpackage, comprising: a sensor control integrated circuit; a molded fillmaterial formed to at least partially encapsulate the sensor controlintegrated circuit; a sensing side redistribution layer disposed on asensing side of the package, wherein the sensing side redistributionlayer comprises at least one passivation layer and a metal layer,wherein the metal layer of the sensing side redistribution layer furthercomprises metal redistribution traces and a metal sensor array in thesensing side redistribution layer, the metal sensor array furtherincluding a plurality of capacitively coupled drivers and pick-upsconfigured to detect ridges and valleys of a fingerprint; a connectionside redistribution layer disposed on a connection side of the package,wherein the connection side of the package is on an opposite side of thepackage relative to the sensing side; at least one ball grid arrayelectrical connector mounted on the connection side redistributionlayer; and a protective coating on the sensing side of the packagedisposed on the sensing side redistribution layer, wherein the at leastone passivation layer comprises a first passivation layer disposedbetween the sensor control integrated circuit and the metal layer. 10.The package of claim 9, wherein the at least one passivation layerfurther comprises second passivation layer, wherein the metal layer isdisposed between the first passivation layer and the second passivationlayer.
 11. The package of claim 1, further comprising: a secondaryintegrated circuit formed within the molded fill material along with thesensor control integrated circuit.
 12. The package of claim 11, whereinthe secondary integrated circuit includes a light emitting diode.
 13. Abiometric object sensor wafer level fan out package, comprising: asensor control integrated circuit; a molded fill material formed to atleast partially encapsulate the sensor control integrated circuit; asensing side redistribution layer disposed on a sensing side of thepackage, wherein the sensing side redistribution layer comprises atleast one passivation layer and a metal layer, wherein the metal layerof the sensing side redistribution layer further comprises metalredistribution traces and a metal sensor array in the sensing sideredistribution layer, the metal sensor array further including aplurality of capacitively coupled drivers and pick-ups configured todetect ridges and valleys of a fingerprint; a connection sideredistribution layer disposed on a connection side of the package,wherein the connection side of the package is on an opposite side of thepackage relative to the sensing side; at least one ball grid arrayelectrical connector mounted on the connection side redistributionlayer; and a protective coating on the sensing side of the packagedisposed on the sensing side redistribution layer, wherein theconnection side redistribution layer comprises a multilayer printedcircuit board.